Question

What is the range of f(x)=5-e^-x

Answer 1

- infinity < f(x) < 5

Answer 2

If you look at a plot of the function, you can see it goes from - infinity to almost 5
http://www.wolframalpha.com/input/?i=plot+5-e%5E-x

Answer 3

I don't understand why it's not infinity to 5

Answer 4

Well because the exponential function has asymptotic behavior at that point. It gets infinitely close to 5, but never actually gets to 5 :)

Answer 5

And the reason it goes from -infinity is because there is a minus sign in front of the e^-x term

Answer 6

So if it was +e^-x then it would be 5, infinity

Answer 7

It would be 5<f(x)<infinity, yup :))
http://www.wolframalpha.com/input/?i=plot+5%2Be%5E-x

Answer 8

Can you help me with another problem?

Answer 9

I'm sorry I have to go but other people on this site would be more than happy to so post away :)

Answer 10

Okay thanks anyway